1.build

2.does-do

3.have

4.doesn't like

5.Does-start

kiểm tra gì bé

xấu xí

\(\left|x\right|+\left|x+2\right|=0\\ TH1:x+x+2=0\\ 2x+2=0\\ 2x=0-2\\ 2x=-2\\ x=-2:2\\ x=-1\\ TH2:-x+\left(-x\right)+2=0\\ -2x=0-2\\ -2x=-2\\ x=-2:\left(-2\right)\\ x=1\)

\(A=1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{2012}}\\ 2A=2+1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{2011}}\\ 2A-A=\left(2+1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^{2011}}\right)-\left(1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{2012}}\right)\\ A=2-\dfrac{1}{2^{2012}}\\ A=\dfrac{2^{4024}-1}{2^{2012}}\)

D